Numerical Simulation of the Flow in an Open Cavity with Heat and Mass Transfer - Selected Topics of Computational and Experimental Fluid Mechanics - page 347

flow velocity the hotter is the cavity. As expected, on the right side of the heater the
contours are distorted and follow the main stream direction toward the outlet of the
cavity. The two vortices associated to the heater transport hot fluid heating the main
stream of fluid. The interaction of the solid heater with the flow generates a thermal
boundary layer separation which is recirculated there by increasing the heat transfer
from the heater to the fluid.
Figure 4 shows the concentration contours for W p = 5. The top panel shows

the behavior of the concentration inside the cavity for Re

W /

10, where gradual
reduction of the concentration can be observed along the fluid motion path due to the
heating decomposition of the substance. At the entrance the concentration is C A =

=

1.
However, at the neighborhood of the heater it is zero as a consequence of the effect
of the temperature. On the top right corner the concentration also tends to zero as
a result of the heating of the fluid in this region, which is associated with the rise
of the thermal plume. At the exit of the cavity the concentration is practically zero,
meaning that the substance has been completely decomposed. The bottom panel
shows the behavior of the concentration inside the cavity for Re 50. For this case,

incomplete decomposition is observed and the concentration is reduced to only about
50% because the flow velocity increases and the main stream of fluid remains cool.
For Re

=

= 10, the outlet flow concentration was 0.08, while for Re = 50, the outlet

flow concentration was 0.5.
Figure 5 shows the axial velocity profile (left panel), and the temperature profile
(right panel) on the middle vertical line for W p = 5 and three different Reynolds

numbers. From the axial velocity profile, we may observe that this velocity compo-
nent increases as the Reynolds number is increased. On the heater the axial velocity
is zero and increases up to a maximum value to finally decrease to zero on the upper
wall of the cavity. From the temperature profile, it can be appreciated that the tem-
perature is 1 on the heater and starts to reduce as the transversal coordinate increases
and becomes zero at y

W /

5. Furthermore, the temperature is reduced more
rapidly as the Reynolds number is increased.

/ H = 0 .

Fig. 4 Concentration for W p = W / 5. To p R e = 10. Bottom Re = 50